Due to the dependent library of the "cordova-custom-config" plugin, the build may not finish successfully.
The npm package "colors" was released with a bug that caused an infinite loop. The plugin "cordova-custom-config" also uses the npm module "colors", causing the bug.
How to fix it
The error has been fixed and "cordova-custom-config" v5.1.1 has been released. You can select the plugin version on the Cordova plugin settings page.
If the problem occurs with a plugin other than "cordova-custom-config", you can avoid using the version that contains the bug by modifying "package.json" in the root directory of the Monaca project as follows.